That said, if there is any T line that lends itself to deep boring, the Blue Line, with its comparatively tiny loading gauge, would be it, speak nothing of its ability to handle tight turns better even than an IRT trainset can. Thinking of it as a potential "T-Tube" is something that doesn't get done nearly enough, imho.

By my calculation, it is less than 210 feet from DTX (OL northbound) to State (OL southbound) station. That's not a very long walking tunnel. Still, the total distance one would need to walk would be over 1/3 mile (1800 feet).